Field of the Invention
Embodiments disclosed herein generally relate to an apparatus having an anodized gas distribution showerhead.
Description of the Related Art
Plasma enhanced chemical vapor deposition (PECVD) is generally employed to deposit thin films on substrates, such as semiconductor substrates, solar panel substrates, flat panel display (FPD) substrates, organic light emitting display (OLED) substrates, and others. PECVD is generally accomplished by introducing a processing gas into a vacuum chamber having a substrate disposed on a susceptor. The processing gas is energized into a plasma by applying an RF current to the chamber from one or more RF sources coupled to the chamber. The plasma reacts to form a layer of material on a surface of the substrate that is positioned on the susceptor.
RF current seeks to return to the source driving it. Thus, the RF current needs a path to return to the RF power source. When the RF return path is not properly laid out, the RF current returning to the RF power source will likely have a lower potential than the RF current traveling in the chamber to ignite the processing gas into a plasma. If the two currents get close enough, the potential difference between the two currents may cause arcing in the chamber and potentially ignite a parasitic plasma that could affect deposition uniformity and film properties during deposition.
Therefore, there is a need in the art for an apparatus having a properly designed RF return path.